1. Field of the Invention
The present invention relates to a case loading device which may comprise a tape-cassette loading device and such a tape-cassette loading device may comprise one used in a DAT (digital audio tape recorder).
2. Related Art
A tape-cassette loading device in the related art used in a rotary-drum type DAT is now described with reference to FIGS. 1 and 2. The tape-cassette loading device includes a chassis 71, holder driving mechanism unit 74 and holder 76.
The chassis 71 includes a top plate 71a, side plates 71b and 71c and long holes 71d and 71e are formed in the top plate 71a. Guide holes are formed in the side plates 71b and 71c, through which holes engaging pins 76e through 76h of the holder 76 and engaging pins 75c and 75d of the holder driving mechanism unit 74 pass.
The holder 76 includes a top plate 76a, side plates 76b and 76c and bottom plate facing the top plate 76a and forms a frame like housing. The engaging pins 76e, 76f, 76g and 76h project from the side plates 76b and 76c.
The holder driving mechanism unit 74 includes a top plate 74a and side plates 74b and 74c and pins 75a and 75b project from the top plate 74a and are inserted into the long holes 71d and 71e formed in the chassis 71. The pins 75c and 75d respectively project from the side plates 74b and 74c and are inserted into the guide holes extending along the D.sub.1 /D.sub.2 directions in the side plates 71b and 71c of the chassis 71. The above pins 75a, 75b, 75c and 75d support the holder driving mechanism unit 74 on the chassis 71 so that the holder driving mechanism unit 74 may move along the D.sub.1 /D.sub.2 directions on the chassis 71.
Guiding holes are formed in the side plates 74b and 74c of the holder driving mechanism unit 74, through which holes the engaging pins 76e, 76f, 76g and 76h pass. The engagement of the engaging pins 76e through 76h with the corresponding guiding holes of the holder driving mechanism unit and with the corresponding guiding holes of the chassis 71 defines the position of the holder 76 on the holder driving mechanism unit 74 so that the position of the holder 76 cannot move on the holder driving mechanism unit 74 in the D.sub.1 /D.sub.2 directions.
An ejecting arm 77 is rotatably supported on the top plate 74a of the holder driving mechanism unit 74 using a shaft 77a and an ejecting arm 81 is rotatably supported on the top plate 74a using a shaft 81a. Rollers 82a and 82b are respectively provided on tips of the ejecting arms 77 and 81 and a roller 83 is provided on the other tip of the ejecting arm 77.
A linkage plate 78 is rotatably supported on the ejecting arm 77 by means of a shaft 84 and is also rotatably supported on the ejecting arm 81 by means of a shaft 80. An end of a spring 79 is hooked on a hooking portion 78a of the linkage plate 78 and the other end of the spring 79 is hooked on a hooking portion 74d of the top plate 74a. The spring 79 pulls the linkage plate 78 in the E.sub.1 direction so that, via the linkage plate 78, the ejecting arm 77 bears the force for rotating the arm 77 counterclockwise and the ejecting arm 81 bears the force for rotating the arm 81 clockwise.
A cut-out portion 72 for guiding the roller 83's movement is formed in the top plate 71a of the chassis 71.
An operation of the above tape-cassette loading device is now described. FIG. 1 shows a state of the device in which the rollers 82a and 82b are in contact with the front end (the lid portion) 30b of a tape cassette 30 and in the state where the tape-cassette has just started to be ejected from the holder 76. FIG. 2 shows a state of the device in which the ejection of the tape cassette 30 from the holder has been completed.
As shown in FIG. 2, the holder 76 is in the position where the holder 76 has moved in the D.sub.2 direction as far as possible and this position is referred to as an inserting position with no tape cassette is loaded in the device. If an operator pushes the tape cassette 30 in the D.sub.1 direction after inserting the cassette in the same direction into the holder 76, the cassette 30 is held in the holder 76 at a predetermined position.
During this period, the front edge 30b of the cassette 30 presses the rollers 82a and 82b of the ejecting arms 77 and 81 so as to rotate the ejecting arm 77 clockwise and to rotate the ejecting arm 81 counterclockwise. Thus, the roller 83 moves to come into contact with a preventing portion 72a.
Then, a holder driving motor is operated so that the holder mechanism unit 74 is driven by the motor in the D.sub.1 direction, the holder 76 being accordingly driven to arrive at a loaded position.
The loaded position is a position where both the mechanism unit 74 and the holder 76 have moved as far as possible in the D.sub.1 direction. While the holder 76 moves to and thus arrives at the loaded position, the ejecting arm 77 is rotated clockwise because the roller 83 of the ejecting arm 77 is guided by the cut-out portion 72, and the ejecting arm 81 is thus rotated counterclockwise via the linkage plate 78. Thus, both the rollers 82a and 82b lose contact with the front edge 30b of the cassette 30.
In order to eject the tape cassette which has been carried by the holder 76 to the holder's loaded position, the holder driving motor drives the holder driving mechanism unit 74 to move it in the D.sub.2 direction. Accordingly, the holder 76 is also moved in the D.sub.2 direction so as to arrive at the inserting position.
When the holder driving mechanism unit 74 arrives at the position shown in FIG. 1, the roller 83 of the ejecting arm 77 comes into contact with the preventing portion 72a. If the holder driving mechanism unit 74 is further moved in the D.sub.2 direction, the roller 83 passes the preventing portion 72a. Then, while the roller 83 rolls on an arc portion 72b, the ejecting arm 77 is rotated counterclockwise due the pulling force of the spring 79 via the linkage plate 78 and the ejecting arm 81 is rotated clockwise accordingly.
The rollers 82a and 82b of the rotated ejecting arm 77 and 81 push the front edge 30b of the cassette 30 in the D.sub.2 direction so that the cassette 30 is ejected from the holder 76. An engaging portion 74e stops the rotation of the ejecting arm 77 when an engaging portion 77b of the arm 77 comes into contact with the engaging portion 74e.
A tape-cassette loading device in the related art such as described above uses a spring's elastic force. The above described device uses the elastic force of the spring 79 for rotating the arm 77 and 81 so as to push out a tape cassette 30 from the holder 76.
However, because a spring's elastic force may vary among the products, the force is required to be large enough to push out the cassette 30 from the holder 76 against friction force preventing the cassette 30 from moving in the holder. Further, the force is required to be large enough to push the cassette 30 to move it by a predetermined distance from the holder so that an operator may reach the cassette 30 from outside to take it out. Such a large elastic force may push the cassette 30 unnecessarily suddenly and rapidly.